When England was conquered by the
Anglo-Saxons were the Celts gradually pushed back to the west. The area
that held out the longest was Wales, even though it was divided into
several small principalities. The map above show the most important. The
title of the Welsh rulers can either be translated to king or prince. One
of them was often powerful enough to claim overlordship over the others
as "king of the Britons" (i.e. the Welsh)
and thus lead the resistance against the Englishmen. They could however
not prevent England's gradual conquest of the country. It was the
flatter areas in southeast Wales which were first subjugated by England
while western Wales and the mountainous inner parts of Wales had more
favourable geography to resist English advances. The last principality
to be conquered by England was Gwynedd in the northwest, it perished 1283.
This had usually been the most powerful Welsh state and several of its
rulers had been "kings of the Britons". The second most important
principality was Deheubarth in the southwest., but the territory of this
state was greatly reduced in the 13th century and it became an
insignificant client state to Gwynedd and was conquered with it by
England 1283.

Wales was conquered by England 1283. Apart from a
rebellion led by Owain Glyndŵr 1400-1415 have Wales thereafter
always been united with England and title "prince of Wales"
has since then been reserved to the oldest son of the king of England.

= Welsh rulers who styled themselves "king of the Britons" and
thus was the overlord of all other Welsh ruler. From the 12th century was
the title replaced with "prince of Wales". = king
of
England/Great
Britain